This application claims the priority of Korean Patent Application No. 2003-15197, filed on Mar. 11, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a method for manufacturing a material film, a capacitor formed using the method, and a method for manufacturing the same. More specifically, the present invention relates to a method for manufacturing an oxide film having high dielectric constant, a capacitor having a dielectric film formed using the method, and a method for manufacturing the same.
2. Description of the Related Art
As the integration density of semiconductor devices, such as DRAMs, increases, manufacturing gate oxide films or capacitors using a silicon oxide (SiO2) film becomes more complicated. Thus, more attention is given and studies are done for materials having a dielectric constant that is higher than that of the silicon oxide film.
Materials having high dielectric constant (hereinafter, referred to as “high k-dielectric materials”) are aluminum oxide (Al2O3) films, hafnium oxide (HfO2) films, and the like. In particular, there have been intensive studies on multi-layered structures in which an aluminum oxide film having relatively low leakage current and a hafnium oxide film having relatively high dielectric constant are sequentially stacked.
In recent years, attempts have been made to form capacitors or gate oxide films of DRAMs using high k-dielectric materials, such as HfO2, ZrO2, and SrTiO3. However, in a metal/insulator/silicon (MIS) structure in which a lower electrode is formed of silicon (Si), since the high k-dielectric materials generally have low band offset, leakage current increases. For this reason, it is actually difficult to apply these high k-dielectric materials to the MIS structure.
As a result, a method for forming an aluminum oxide film, which has relatively low dielectric constant and high band offset for a silicon film, between a silicon film and a high k-dielectric material is being developed to reduce the leakage current. For example, costly studies are being done on a multi-layered structure in which a silicon film, an aluminum oxide (Al2O3) film, and a high k-dielectric material are sequentially stacked.
FIGS. 1 through 3 show a conventional method of manufacturing a high k-dielectric oxide film as a multi-layered structure.
Referring to FIG. 1, an oxidation barrier film 12 is formed on a silicon film 10. The oxidation barrier film 12 is a nitride film formed using rapid thermal process (RTP). After the oxidation barrier film 12 is formed, as shown in FIG. 2, an aluminum oxide film 14 is formed on the oxide barrier film 12. Next, as shown in FIG. 3, a hafnium oxide film 16 having a dielectric constant that is higher than that of the aluminum oxide film 14 is formed on the aluminum oxide film 14. Reference numeral 18 denotes an imagined upper electrode formed of polysilicon.
In the conventional method for manufacturing a high k-dielectric oxide film, by which an aluminum oxide film and a hafnium oxide film are sequentially stacked, the capacitance of a capacitor cannot be sufficiently increased due to low dielectric constant of the aluminum oxide film. Also, because the aluminum oxide film and the hafnium oxide film must be formed at different temperatures, two different atomic layer deposition (ALD) apparatuses are required.
That is, according to the conventional method, at least two ALD apparatuses are required. Also, the deposition rate of a hafnium oxide film is lower than that of an aluminum oxide film, thus lowering the productivity. Further, as a high k-dielectric oxide film may be crystallized during a thermal treatment performed after a capacitor is completed, the leakage current may increase.